Median Nerve Cross-sectional Area Research Articles

Changes in Ultrasound Parameters of the Median Nerve at Different Positions of the Radiocarpal Joint in Patients with Carpal Tunnel Syndrome.

Ultrasound imaging (US) is being increasingly used to aid in the diagnosis of entrapment neuropathies. This study aims to evaluate the shear modulus and cross-sectional area (CSA) of the median nerve in patients with carpal tunnel syndrome (CTS). A total of 35 patients with CTS participated in the study. CSA and shear modulus testing were performed in shear wave elastography (SWE) mode in five positions of the right and left radiocarpal joints (intermediate position 0°, 45° of extension, maximum extension, 45° of flexion, and maximum flexion). There were significant side-to-side differences in the median nerve shear modulus at each wrist position as compared to the asymptomatic side. There were significant side-to-side differences in the median nerve CSA at each wrist position as compared to the asymptomatic side. Shear modulus increases in patients with CTS at different angular positions of flexion and extension of the radiocarpal joint. In individuals with CTS, the CSA of the median nerve is greater on the symptomatic side compared to the asymptomatic side. The CSA decreases in positions of maximum extension and 45° of flexion and in maximum flexion relative to the resting position.

Comparison of the Effect of Out-of-plane and In-plane Injection Approaches on Injection Pain and Functionality in Patients with Carpal Tunnel Syndrome Undergoing Ultrasound-guided Injection: A Patient- and Assessor-blinded Randomized Study

ObjectivesThe aims were i) to compare the out-of-plane (OP) and in-plane (IP) approaches for carpal tunnel syndrome (CTS) in terms of pain during injection and post injection adverse effects, and ii) to investigate whether these approaches led to any difference in terms of pain/numbness, symptom severity, functionality, and median nerve cross-sectional area and to examine the relationship of these parameters with the pain during injection. DesignPatient/assessor blinded randomized study SettingHospital outpatient clinic. ParticipantsFifty patients with mild to moderate CTS. InterventionsThe participants were randomized into OP and IP (both n = 25) ultrasound-guided injection groups. Main outcome measuresEach patient reported the pain felt during the injection at 1 h thereafter, and also any adverse effects at 4 weeks after injection. Before and 4 weeks after injection, patients used a visual analog scale to indicate pain/numbness; symptom severity and functionality were assessed using the Boston Carpal Tunnel Syndrome Questionnaire. The cross-sectional area of the median nerve was also obtained. ResultsThe average pain during injection was 2.64±0.82 in the IP group and 1.96±0.86 in the OP group (p=0.017). Post-injection adverse effects were similar between the two groups (p<0.05). After injection, the percentage change in symptom severity was 49.8±11.8 in the IP group and 40.6±11.5 in the OP group (p=0.008). In the IP group, day pre-injection pain/numbness, night pain/numbness percentage change scores, and symptom severity percentage change scores were moderately correlated with the pain during injection (r=0.439, 0.469, and 0.429, respectively). ConclusionsIP injection caused greater pain during injection compared to OP injection and led to greater reduction in symptom severity at 1 month after injection. In that group, injection pain was associated with the baseline day pain score, change in night pain score, and change in symptom severity score.

Median Nerve Cross-Sectional Area and Carpal Tunnel Syndrome in Specific Populations: Sonographic Analysis of Patients with Type 2 Diabetes or Bifid Anatomy.

Evaluate diagnostic accuracy of median nerve cross-sectional area (CSA) to determine severity versus presence of carpal tunnel syndrome (CTS) across existing electrodiagnostic-based (EDX) classification systems in patients with type 2 diabetes or bifid anatomy. Retrospective analysis of cross-sectional patient data. Receiver operating characteristic analysis used to determine median nerve CSA cutoff values and associated diagnostic likelihood ratios for all consolidated and binary EDX-based classifications of CTS in patients with type 2 diabetes or bifid anatomy. Determine shifts in diagnostic probability based on established cutoff values and associated likelihood ratios. Distal CSA measured at or near carpal tunnel inlet, proximal CSA at level of pronator quadratus muscle, and delta CSA by subtracting proximal from distal. Binary categorizations of CTS were statistically superior to consolidated categorizations of CTS severity in patients with type 2 diabetes or bifid anatomy. Binary categorizations established reasonably consistent median nerve CSA cutoff values across all EDX-based classifications examined resulting in the following for distal CSA or delta CSA: ≤10 or ≤4 mm2 to rule out and ≥11 or ≥5 mm2 to rule in CTS, respectively. These cutoff values resulted in small shifts in diagnostic probability in patients with type 2 diabetes and small to conclusive shifts in diagnostic probability in patients with bifid anatomy. Binary categorizations to rule out or rule in CTS based on the proposed cutoff values provide the most meaningful information about shifts in diagnostic probability across all EDX-based classifications examined. The use of median nerve CSA to categorize severity of CTS is not recommended in patients with type 2 diabetes or bifid anatomy.

Sonographic Measurement of Median Nerve Cross-Sectional Area to Determine Severity of Carpal Tunnel Syndrome: A Cautionary Tale.

Evaluate the diagnostic accuracy of median nerve cross-sectional area (CSA) to determine the severity of carpal tunnel syndrome (CTS) vs the presence of CTS across existing electrodiagnostic-based (EDX) classification systems. Retrospective analysis of cross-sectional patient data. Receiver operating characteristic (ROC) analysis was used to determine CSA cutoff values and associated diagnostic likelihood ratios for all consolidated and binary EDX-based classifications of CTS severity. Identification of CSA cutoff values associated with likelihood ratios capable of achieving conclusive (but at least moderate) shifts in diagnostic probability. Binary categorizations of CTS (ie, "Normal" vs "Absent") were statistically superior to consolidated categorizations of CTS severity (ie, "Normal," "Mild," "Moderate," or "Severe"). Binary categorizations established consistent CSA cutoff values across all EDX-based classifications examined and achieved conclusive shifts in diagnostic probability based on the following values of distal CSA or delta CSA: <7 or <1 mm2 to rule out and >13 or >7 mm2 to rule in CTS, respectively. Additionally, the following values of distal CSA and delta CSA may be used in certain circumstances because they produce only small shifts in diagnostic probability: ≤10 or ≤3 mm2 to rule out and ≥11 or ≥4 mm2 to rule in CTS, respectively. Using median nerve CSA to categorize the severity of CTS is not recommended based on lack of consistent and meaningful shifts in diagnostic probability. Rather, binary categorizations to rule out or rule in CTS based on the proposed CSA cutoff values consistently provided conclusive shifts in diagnostic probability across all EDX-based classifications examined.

Ultrasound-Guided Modified Thread Carpal Tunnel Release for Carpal Tunnel Syndrome: A Pilot Study.

This study aimed to investigate the effectiveness and safety of modified thread carpal tunnel release (mTCTR) using Smartwire-01 in patients with carpal tunnel syndrome (CTS). Patients with CTS who required CTR were enrolled. Symptom severity and functional status were assessed using the Boston Carpal Tunnel Syndrome Questionnaire-Symptom Severity Scale (BCTQ-SSS) and Functional Status Scale (BCTQ-FSS), and pain was assessed using a numerical rating scale (NRS) at 4, 8, and 12 weeks after mTCTR. The scores were compared with the pre-procedural scores. The electrophysiologic study and median nerve cross-sectional area (CSA) measurements at the wrist before and 12 weeks after mTCTR were compared. A total of 11 patients were included. No adverse effects were reported throughout the study period. The NRS, BCTQ-SSS, and BCTQ-FSS scores significantly improved at 4 weeks after mTCTR, and this improvement persisted throughout the follow-up period (NRS and BCTQ-SSS, P < 0.001; BCTQ-FSS, P = 0.012). After 12 weeks, the latency and velocity of the median sensory nerve action potential significantly improved, compared with those before mTCTR (latency, 5.4 ± 1.3 to 4.7 ± 1.1 ms, P = 0.01; velocity 27.8 ± 6.8 to 31.8 ± 7.4 m/s, P = 0.019). No significant change was observed in the median nerve CSA before and after mTCTR. mTCTR using Smartwire-01 is a safe and effective procedure and a possible alternative to surgery.

Elastography of nerves in the wrists of cyclists.

This study aimed to investigate changes in the elasticity of the median and ulnar nerves in cyclists. The study included 30 cyclists and 2 non-biking reference groups that included 32 healthy volunteers and 32 individuals with ulnar nerve entrapment neuropathies. All participants underwent physical, ultrasonographic, and elastographic examinations including assessment of nerve cross-sectional area (CSA) and stiffness (SWE). The cyclists' group was tested before and after a 2-hour workout. The values of ulnar nerve CSA and stiffness in Guyon's canal in resting cyclists were 5.30 ± 1.51 mm2 and 49.05 ± 11.18 kPa, respectively. These values were significantly higher than in the healthy volunteers, but not higher than in the nerve entrapment group. Median nerve CSA and stiffness at rest were 9.10 ± 2.61 mm2 and 38.54 ± 14.87 kPa, respectively. Both values were higher than respective values in the healthy group. Cycling induced an increase in all these parameters, although the increase in nerve stiffness was more noticeable than in CSA. The elasticity of the median and ulnar nerve in cyclists remains within normal limits, questioning the belief that cyclists are at risk of nerve palsy in Guyon's canal. However, cycling workout does exert compression, resulting in transient oedema of both nerves. The dynamics of changes was more noticeable in SWE examination than in conventional ultrasound, which may depend on SWE sensitivity.

Determining Optimal Cut-Off Value For Ultrasound-Measured Median Nerve Cross-Sectional Area For Diagnosis Of Carpal Tunnel Syndrome In A Sample Of Egyptian Population

Determining Optimal Cut-Off Value For Ultrasound-Measured Median Nerve Cross-Sectional Area For Diagnosis Of Carpal Tunnel Syndrome In A Sample Of Egyptian Population

Assessment of sonographic measurement of the median nerve cross-sectional area in pregnant women with hypertensive disorders

Assessment of sonographic measurement of the median nerve cross-sectional area in pregnant women with hypertensive disorders

Association between electrodiagnosis and neuromuscular ultrasound in the diagnosis and assessment of severity of carpal tunnel syndrome.

Neuromuscular ultrasound plays an increasing role in diagnosing carpal tunnel syndrome (CTS). There are limited data supporting the correlation between the electrodiagnostic studies and ultrasound measurements in CTS. To assess the association between different electrodiagnostic severities and ultrasound measurements of the median nerve in CTS. A retrospective cohort study. An academic tertiary care center. Patients 18 years or older evaluated with upper limb electrodiagnostic studies and neuromuscular ultrasound. Ultrasound measurements of the median nerve cross-sectional area (CSA) at the wrist and the calculated wrist-to-forearm ratio (WFR) were compared with the electrodiagnostic severity (normal, mild, moderate, and severe). Mean analysis and analysis of variance test (α = 0.05) were performed to assess the association. A total of 1359 limbs were identified. There was a statistically significant association between electrodiagnostic severity of CTS and median nerve CSA at the wrist (p < .001), as well as the WFR (p < .001). The mean median nerve CSA at the wrist and WFR were 7.01 ± 2.06 mm2 (95% CI: 6.80-7.20) and 1.24 ± 0.36 (95% CI: 1.16-1.24) in electrodiagnostically normal median nerves, 10.47 ± 2.82 mm2 (95% CI: 10.25-10.75) and 2.06 ± 0.67 (95% CI: 2.04-2.16) in electrodiagnostically mild CTS, 12.95 ± 4.74 mm2 (95% CI: 12.41-13.59) and 2.49 ± 1.04 (95% CI: 2.37, 2.63) in electrodiagnostically moderate CTS, and 14.69 ± 5.38 mm2 (95% CI: 13.95-15.44) and 2.71 ± 1.02 (95% CI: 2.56-2.84) in electrodiagnostically severe CTS, respectively. This study suggests a direct association between electrodiagnostic severity and ultrasound measurements of the median nerve in patients with suspected CTS.

Diagnostic efficacy of high-frequency Grey-scale ultrasonography and Sono-elastography in grading the severity of carpal tunnel syndrome in comparison to nerve conduction studies.

To correlate the cross-sectional area (CSA) and elasticity of the median nerve (MN) measured at carpal tunnel inlet between healthy controls and various degrees of carpal tunnel syndrome (CTS) graded as per nerve conduction studies (NCS). A total of 53 patients (with 81 wrists) presenting with clinical symptoms characteristic of CTS, having their diagnosis confirmed and severity graded by NCS, and 48 healthy controls (with 96 wrists) were included in the study. All the study participants underwent wrist ultrasound which included initial Grey-scale USG followed by strain and shear wave elastography. The CSA and elasticity (in terms of strain ratio and shear modulus) of MN were measured at the carpal tunnel inlet. Statistical analysis was performed using the Mann-Whitney U test to compare between the two groups and for subgroup analysis of cases. The diagnostic performance of each variable was evaluated using the receiver operating characteristic curves. The mean CSA was 9.20 ± 1.64, 11.48 ± 1.05, 14.83 ± 1.19 and 19.87 ± 2.68 mm2, the mean shear modulus was 17.93 ± 2.81, 23.59 ± 2.63, 32.99 ± 4.14 and 54.26 ± 9.24kPa and the mean strain ratio was 5.26 ± 0.68, 5.56 ± 0.70, 7.03 ± 0.47 and 8.81 ± 0.94 in control, mild, moderate and severe grades of CTS, respectively (p < 0.001). The combined utility of Grey-scale USG and Elastography may serve as a painless and cost-effective alternative to NCS in grading the severity of CTS.

Median Nerve Shear Wave Elastography Is Associated With the Neurophysiological Severity of Carpal Tunnel Syndrome.

This study examines the associations between the median nerve (MN) shear wave elastography (SWE), the MN cross-sectional area (CSA), patient's symptoms, and the neurophysiological severity of carpal tunnel syndrome (CTS). The most appropriate site to perform SWE was also tested. This prospective study comprised 86 wrists of 47 consecutive patients who volunteered for MN ultrasound after an electrodiagnostic study. The neurophysiological severity of CTS was assessed according to the results of a nerve conduction study (NCS). The MN CSA was measured at the carpal tunnel inlet (wCSA) and the forearm (fCSA). SWE was performed on the MN in a longitudinal orientation at the wrist crease (wSWE), at the forearm (fSWE), and within the carpal tunnel (tSWE). The wCSA and wSWE correlated positively with the neurophysiological severity of CTS (r = .619, P < .001; r = .582, P < .001, respectively). The optimal cut-off values to discriminate the groups with normal NCS and with findings indicating CTS were 10.5 mm2 for the wCSA and 4.12 m/s for the wSWE. With these cut-off values, wCSA had a sensitivity of 80% and specificity of 87% and wSWE a sensitivity of 88% and specificity of 76%. Neither tSWE nor fSWE correlated with the neurophysiological severity of CTS or differed between NCS negative and positive groups (P = .429, P = .736, respectively). Shear wave velocity in the MN at the carpal tunnel inlet increases in CTS and correlates to the neurophysiological CTS severity equivalently to CSA measured at the same site.

Application of radiomics model based on ultrasound image features in the prediction of carpal tunnel syndrome severity.

The aim of our study is to develop and validate a radiomics model based on ultrasound image features for predicting carpal tunnel syndrome (CTS) severity. This retrospective study included 237 CTS hands (106 for mild symptom, 68 for moderate symptom and 63 for severe symptom). There were no statistically significant differences among the three groups in terms of age, gender, race, etc. The data set was randomly divided into a training set and a test set in a ratio of 7:3. Firstly, a senior musculoskeletal ultrasound expert measures the cross-sectional area of median nerve (MN) at the scaphoid-pisiform level. Subsequently, a recursive feature elimination (RFE) method was used to identify the most discriminative radiomic features of each MN at the entrance of the carpal tunnel. Eventually, a random forest model was employed to classify the selected features for prediction. To evaluate the performance of the model, the confusion matrix, receiver operating characteristic (ROC) curves, and F1 values were calculated and plotted correspondingly. The prediction capability of the radiomics model was significantly better than that of ultrasound measurements when 10 robust features were selected. The training set performed perfect classification with 100% accuracy for all participants, while the testing set performed accurate classification of severity for 76.39% of participants with F1 values of 80.00, 63.40, and 84.80 for predicting mild, moderate, and severe CTS, respectively. Comparably, the F1 values for mild, moderate, and severe CTS predicted based on the MN cross-sectional area were 76.46, 57.78, and 64.00, respectively.. This radiomics model based on ultrasound images has certain value in distinguishing the severity of CTS, and was slightly superior to using only MN cross-sectional area for judgment. Although its diagnostic efficacy was still inferior to that of neuroelectrophysiology. However, this method was non-invasive and did not require additional costs, and could provide additional information for clinical physicians to develop diagnosis and treatment plans.

Association Between Thenar Musculature and Carpal Tunnel Syndrome.

Background: Dynamic forces acting on the transverse carpal ligament (TCL) may influence the mechanics of the carpal tunnel (CT), thus affecting the occurrence of CT syndrome (CTS). Previous studies demonstrated an association between muscle overlying the CT and the diagnosis of CTS. Understanding the location of insertion/origin of the thenar musculature will allow mechanical analysis of the forces applied to the TCL during performance of individual tasks. Our purpose was to determine the location of muscle overlying the CT on magnetic resonance imaging (MRI) in CTS and controls. Methods: Case-control study of 21 normal adult wrist MRI scans. MRI measurements were performed on an axial cut at the level of the hook-of-hamate. Median nerve cross-sectional area (CSA), median nerve shape and increased signal intensity within the CT were associated with CTS. The amount and length of muscle crossing the midline and the CT on the same cut was measured and the association with the occurrence of CTS was analysed. Results: We found an inverse relationship between the amount of muscle crossing the midline and the size of the CT, and a direct relationship with occurrence of CTS p less than 0.01, but no differences regarding length of muscle crossing the midline. Conclusions: This study supports an association between the thenar musculature location relative to the CT and the predictors of CTS on MRI. Since the location of muscle origin/insertion is variable, their effect may differ accordingly, therefore, further study is needed to describe the exact location of origin/insertion and its differential dynamic or static effect on the pathogenesis of CTS. Level of Evidence: Level IV (Diagnostic).

Ultrasonographic Assessment of Median Nerve Cross-Sectional Area in Obstetricians

Ultrasonographic Assessment of Median Nerve Cross-Sectional Area in Obstetricians

Diagnostic Ability of Nerve Conduction Study, Ultrasonography and Magnetic Resonance Imaging in Diagnosis of Carpel Tunnel Syndrome

Introduction: Current diagnostic criteria for Carpel Tunnel Syndrome (CTS) include a patient's medical history, physical exam results, and electrophysiological findings. The purpose of the study is to evaluate the diagnostic ability of nerve conduction study, ultrasonography and magnetic resonance imaging for the diagnosis of carpal tunnel syndrome with the use of clinical findings as the gold standard.&#x0D; Methodology: The study was conducted among 30 patients clinically diagnosed having CTS based on the criteria given by American Academy of Neurology and American Academy of Physical Medicine and Rehabilitation. All patients included in the study were underwent USG of affected wrist joint, CT scan as well MRI of the same.&#x0D; Results: Out of total 30 participants, 14 (46.7%) were found moderate severity followed by 11 (36.7%) were found mild severity. Only 5 (16.7%) were found severe carpel tunnel syndrome. Amongst all three investigation methods, nerve conduction study having the lowest sensitivity (83.33%). The sensitivity of the ultrasonography and MRI was 90% each.&#x0D; Conclusion: It is clear from this study that the sensitivity of the parameters utilized in NCS (maximum observed 83.33%) is lower than that of the median nerve cross-sectional area detected on USG (90%) and MRI (90%). The most sensitive, practical, and cost-effective metric of all those seen in the research turned out to be the median nerve cross sectional area evaluated at the wrist crease by USG.

Ultrasonographic changes of the median nerve in patients with end-stage renal failure and comparing it with a control group

Carpal Tunnel Syndrome (CTS) is characterized by median nerve entrapment in the wrist. CTS is diagnosed by clinical symptoms, which are confirmed by electrodiagnostic studies. This study aimed to assess median nerve cross-sectional area and elastography in chronic hemodialysis patients. This case-control study was conducted on end-stage renal failure (ESRD) patients undergoing hemodialysis at Rasool Akram Hospital's Dialysis Unit. The healthy companions of the patients were included as control group. An experienced rheumatologist used a supersonic device with linear array probes and dynamic scanners (5-22 MHz) to perform the sonography. The current study was conducted on both hands. There was no statistically significant difference between 30 patients and 30 healthy individuals regarding age, weight, and body mass index. The cross sectional area of median nerve in both hands was increased in the dialysis group compared to the control group. However, it was significantly higher in the patient group's right hand than in the control group (P = 0.031). Considering the causes of ESRD and parathormone levels, the cross-sectional area and mean right and left median nerve elastography were not different between the two groups. The results showed that the patient group had a larger right and left median nerve cross-sectional area than the control group. However, the median nerve elastographic indices did not differ between dialysis patients and healthy individuals.

Characteristics of diabetic and non-diabetic carpal tunnel syndrome in terms of clinical, electrophysiological, and Sonographic features: a cross-sectional study

BackgroundAlthough diabetes is considered a major risk factor for carpal tunnel syndrome (CTS), the characteristics of diabetic CTS have not been fully understood.ObjectiveThis study is aimed at evaluation of the clinical, electrophysiological, and ultrasonographic findings of non-diabetic and diabetic CTS.MethodsThis retrospective, cross-sectional study included patients diagnosed with CTS. Patient age, sex, involved side, body mass index, clinical and electrophysiological findings, and median nerve cross-sectional area (CSA) were identified. Diabetes was identified through patient or guardian interviews, medical records, and medication history. Linear and binary logistic regression models were established to confirm the associations between the electrophysiological findings, median nerve CSA, and clinical outcomes. Covariates, such as age, sex, body mass index, diabetes, symptom duration, and thenar muscle weakness were adjusted.ResultsOut of the 920 hands, 126 and 794 belonged to the diabetic and non-diabetic CTS groups, respectively. The patients were significantly older in the diabetic CTS group (P < 0.001). The rate of thenar weakness in the diabetic CTS group was also significantly higher than that in the non-diabetic CTS group (P = 0.009). The diabetic CTS group had a more severe electrodiagnostic grade (P = 0.001). The prolonged onset latency of the compound motor nerve action potential (CMAP) and median nerve CSA were well associated with the degree of clinical symptoms. Increased median nerve CSA was significantly associated with prolonged CMAP onset latency (β = 0.64; P = 0.012), prolonged transcarpal latency (β = 0.95; P = 0.044), and decreased CMAP amplitude (β = -0.17; P = 0.002) in the non-diabetic CTS group.ConclusionDiabetic CTS had more profound electrophysiological abnormalities. Distal motor latency and median nerve CSA were not only associated with each other, but also with clinical symptoms. Further studies are needed to investigate the pathophysiological mechanisms underlying diabetic CTS.

Retracted: Effect of Wrist Dorsiflexion/Palmar Flexion on Median Nerve Deviation and Cross-Sectional Area in Patients with Carpal Tunnel Syndrome.

[This retracts the article DOI: 10.1155/2023/3631193.].

Does hot pack application change the morphology of the median and ulnar nerves?

This study aims to investigate the effect of the hot pack application on the morphology of healthy median and ulnar nerves. Between August 2021 and September 2022, a total of 54 healthy volunteers (17 males, 37 females; mean age: 31.9±9.4 years; range, 21 to 63 years) were included in the study. The cross-sectional area (CSA) and depth of the right median and ulnar nerve were measured using ultrasonography before and after 20-min hot pack application. The right median nerve CSA and depth from the level of the scaphoid bone (at the level of the carpal tunnel) and from the mid-forearm were also measured. The right ulnar nerve CSA and depth from the level of the hook of hamate and the mid-forearm were evaluated. The depth measurements between the skin and the outer hyperechoic border of the nerve were performed. After the hot pack application, there was an increase in both the median nerve CSA at the carpal tunnel (from 0.06±0.01 to 0.09±0.02 cm2 ) and forearm (from 0.06±0.02 to 0.09±0.02 cm2 ) levels (p<0.001) and the ulnar nerve CSA at the hook of hamate (from 0.04±0.03 to 0.06±0.01 cm2 ) and forearm (0.05±0.01 to 0.08±0.02 cm2 ) levels (p<0.001). No statistically significant difference was observed between the pre- and post-application depth measurements (p>0.05). Our study results show that the hot pack application leads to acute swelling of the median and ulnar nerves. In future studies, the relationship between morphological changes in healthy and pathological nerves and electrodiagnostic findings should be investigated.

Sonographic evaluation of median nerve cross-sectional area in a normal Iranian population: A cross-sectional study.

Considering disagreements on the normal range of median nerve cross-sectional area (MNCSA) and insufficient data in the Iranian population, this study aimed to measure normal MNCSA. In this cross-sectional study, bilateral upper limbs of 99 subjects were assessed by sonography, and MNCSA was measured at three levels: forearm, carpal tunnel inlet (CTI), and carpal tunnel outlet (CTO). The association between MNCSA and demographic factors was assessed. Mean MNCSA was 6.33 mm2 at the forearm, 9.41 mm2 at CTI, and 10.67 mm2 at CTO. MNCSA was significantly higher in males (6.78 vs. 5.94 mm2 at the forearm, 9.98 vs. 8.92 mm2 at CTI, and 11.24 vs. 10.84 mm2 at CTO in males and females, respectively) and taller (>170 cm) subjects in all three levels (6.69 vs. 6.03 mm2 at the forearm, 9.80 vs. 9.02 mm2 at CTI, and 11.27 vs. 10.12 mm2 at CTO in taller and shorter subjects, respectively). MNCSA was not significantly associated with wrist ratio (WR) or body mass index (BMI). The normal MNCSA range in the Iranian population is 6.31 mm2 (forearm) to 10.74 mm2 (CTO). MNCSA is significantly higher in males and taller subjects but is not associated with BMI and WR.